If Tony Soprano isn't careful, his new extramarital affair could torpedo his marriage.

That's why his behavior begs the question: Why does he cheat? 

Since many New York psychologists are fascinated by The Sopranos, I sought input from some of them and they gave me a variety of answers. 

He's addicted to power, said one. 

He has problems with intimacy issues, offered another. 

He's a misogynist and a sociopath, said others. 

Tony has been in therapy for more than 21/2 seasons. He has a wife who loves him and who maintains for him an immaculate home. She's constantly doing laundry, looking after the kids and cooking Italian dishes that are so delicious they can be enjoyed cold. 

And yet, still he strays. 

While Carmela mopes around the house contemplating whether to leave him, he's carrying on with his new girlfriend - the Mercedes saleswoman Gloria Trillo (played by Annabella Sciorra) - aboard his cabin cruiser, the Stugots. 

Hey, docs, what gives? 

"Tony cheats probably for a variety of reasons," theorizes Dr. Alan Hilfer, a psychologist at Maimonides Medical Center in Brooklyn. "He probably has a great deal of unresolved issues based on his ambivalent relationship with his mother, and tends to treat women more as objects than as real potentially intimate partners." 

But his mother's dead. What I want to know is: Why can't he see what his behavior is doing to Carmela? 

"He doesn't have much of a conscience," Dr. Hilfer says. "That's the key and that's how he can do these kinds of things - to have outside relationships and not feel too bad about it." 

But shouldn't his therapy be helping him? 

Well, it would, if Tony were a more committed patient. 

"He's not honest, and therapy is only as effective as a patient's honesty," says Dr. Wylie Goodman, a Manhattan psychologist. 

"He keeps the most disturbing part of his life secret," complains Dr. Art Mones of the Center for Psychological Services at St. John's University. 

"If he wants to look at the things that are underlying his anxiety attacks, he has to be in a place where he can be honest, but of course his code of silence doesn't allow for more direct conversations," says Dr. Alan Manevitz, a psychiatrist and teacher at the Weill Medical College of Cornell University/New York Presbyterian Hospital. 

The experts agree that Tony and Carmela's marriage is at a low ebb, and that Tony's new affair will do nothing to improve the situation. 

"You can't really work on a relationship while you're having an affair on the outside," says Dr. Manevitz. 

Given Tony's wandering ways, can this marriage be saved? Yes, say the experts, but only if Tony or Carmela take drastic action or undergo fundamental change. 

"It requires that at least one of the partners changes in a significant way," says Dr. Goodman. "And I think Carmela is at a point where if she takes very dramatic action to do something that upsets the dynamics of their relationship, then maybe he can change because I don't think he can do it on his own." 

Dr. Manevitz says Tony has to "make a commitment to wanting to work on the marriage." That means "he has to stop seeing [other women] and begin talking about what the issues are [in his marriage] and see if [he and Carmela] can actually talk about trust, respect and kindness, and then to see if they can develop into passion," he says. 

Dr. Mones isn't as optimistic. Says he: "I think a healthy marriage gets to a stage of acceptance, mutual empathy and openness to each other's vulnerabilities. 

"I think because of his secrets [Tony and Carmela] won't get to that healthy stage."